"Bacterial Economics"

If you’re a skier, you’ve probably schussed on snow made with bacteria. Ski resorts use Pseudomonas syringae as an ice nucleator, which means water freezes around the bacteria quickly to form snowflakes. But don’t worry – the bacteria used are dead and harmless.

Now, researchers are finding that P. syringae in its live form could help farmers too. According to a recent study published in the Proceedings of the National Academy of Sciences, these biological ice nucleators are “widespread in the atmosphere and may affect meteorological processes that lead to precipitation.”

Professor Dave Sands at Montana State University was a researcher in the study, and he proposes that if these microbes are, in fact, affecting our rain, modern agriculture could use them to promote crop growth in several ways – one involving weed suppression and another involving rain production.

In a previous study that Sands participated in, researchers found that P. syringae can cause serious damage to some weeds. That could make it a sustainable option for organic farmers who avoid chemical herbicides.

“Agriculture can be flexible,” Sands says. “If you have a choice of a hundred varieties of wheat, why not choose one that tolerates this bacteria really well?”

As far as helping to produce rain, Sands uses the term “bacterial economics” to help hypothesize. If these microbes are spending energy on ice nucleation, what’s in it for them? Self-dispersal is the idea.

Certain species of microorganisms can survive all over the globe, the study says, but not much is known about how. Conclusions from the study emphasize that more detailed investigation is needed to figure out if the microbes are strategically spreading themselves by catalyzing rain in the atmosphere.

Researchers found that 95 percent of the ice nuclei that promoted higher freeze temperatures of water were biological in origin, and a significant portion of those was of bacterial origin. This is important because a speck of dust or soot can be an ice nucleator too, but only at lower temperatures.

A working relationship between university academics and the National Center for Atmospheric Research (NCAR) could prove to be helpful in tracking the microbial dispersal. Sands says that Conservation Reserve Program land in the West could soon be used as launch pads for the microbes. And with satellites, NCAR could track the dispersal of the microbes as they drift through the meteorological ether.

In the end, scientists could help reduce drought in certain areas by releasing P. syringae into the atmosphere to induce rain. This could have been helpful information – oh, let’s say – during the Dust Bowl drought of the 1930s.

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If these microbes are released into the air, would they stay there? How high into the atmosphere would they be released and how sensitive to winds would they be? If they fell to breathable air, would they pose a hazard as particulate matter air pollution?